(CBS/AP) CHARDON, Ohio - A teenager described as an outcast at a suburban Cleveland high school opened fire in the cafeteria Monday, killing one student and wounding four others before he was chased from the building by a teacher and captured a short distance away, authorities said. A student at the school identified the suspected gunman to CBS News as T.J. Lane.

Law enforcement sources tell CBS News that, a day or two ago, the suspect told classmates something of his plans, but those classmates didn't take him seriously.

Another student who saw the attack close-up said it appeared that the gunman targeted a group of students sitting at a cafeteria table and that the one who was killed was trying to duck under the table.

Panicked students screamed and ran through the halls after gunfire broke out at the start of the school day at 1,100-student Chardon High, about 30 miles from Cleveland. Teachers locked down their classrooms as they had been trained to do during drills, and students took cover as they waited for the all-clear.

One teacher was said to have dragged a wounded student into his classroom for protection. And distressed parents thronged the streets around the school as they heard from students via text message and cellphone long before official word came of the attack.

The suspect, whose name was not released because he is a juvenile, was arrested near his car a half-mile away, the FBI said. He was not immediately charged. The Geauga County Sheriff's Office said that the suspect turned himself in after being chased out of the school by a teacher, CBS News has learned.

FBI officials would not comment on a motive. And Police Chief Tim McKenna said authorities "have a lot of homework to do yet" in their investigation. But 15-year-old Danny Komertz, who witnessed the shooting, said the gunman was known as an outcast who had apparently been bullied.

"I looked up and this kid was pointing a gun about 10 feet away from me to a group of four kids sitting at a table," Komertz said. He said the gunman fired two shots quickly, and students scrambled for safety. One of them was "trying to get underneath the table, trying to hide, protecting his face."

The slain student, Daniel Parmertor, was an aspiring computer repairman who was shot while waiting for the bus for his daily 15-minute ride to a vocational center. His teacher at the Auburn Career School had no idea why Parmertor, "a very good young man, very quiet," had been targeted, said Auburn superintendent Maggie Lynch.

"We are shocked by this senseless tragedy," his family said in a statement. "Danny was a bright young boy who had a bright future ahead of him."

Parmertor's teacher at Auburn Career School had no idea why Parmertor, "a very good young man, very quiet," had been targeted, said Auburn superintendent Maggie Lynch.

Officers investigating the shooting blocked off a road in a heavily wooded area several miles from the school. Federal agents patrolled the muddy driveway leading to several spacious homes and ponds, while other officers walked a snowy hillside. A police dog was brought in.

A U.S. official said that a preliminary report shows the suspect fired eight shots, CBS News correspondent Bob Orr reports. The FBI and local police have conducted an extensive search of the home where the suspected shooter lived. (The house belongs to the suspect's grandparents.)

Agents were looking for computer files, phone records, notes and possible weapons, Orr reports. Police are trying to establish a motive for the shootings and are looking for evidence that could show how much planning went into the attack. They are looking through emails, social network postings, and other communications to determine what the suspect may have shared with friends or associates about his intent.

One law enforcement source says the suspect "is cooperating" with police.

Teacher Joe Ricci had just begun class when he heard shots and slammed the door to his classroom, yelling, "Lock down!" to students, according to Karli Sensibello, a student whose sister was in Ricci's classroom.

A few minutes later, Ricci heard a student moaning outside, opened the door and pulled in student Nick Walczak who had been shot several times, Sensibello said in an email. Ricci comforted Walczak and let him use his cellphone to call his girlfriend and parents, Sensibello said. She said her sister was too upset to talk.

Heather Ziska, 17, said she was in the cafeteria when she saw a boy she recognized as a fellow student come into the cafeteria and start shooting. She said she and several others immediately ran outside, while other friends ran into a middle school and others locked themselves in a teachers' lounge.

"Everybody just started running," said 17-year-old Megan Hennessy, who was in class when she heard loud noises. "Everyone was running and screaming down the hallway."

Rebecca Moser, 17, had just settled into her chemistry class when the school went into lockdown. The class of about 25 students ducked behind the lab tables at the back of the classroom, uncertain whether it was a drill.

Text messages started flying inside and outside the school, spreading information about what was happening and what friends and family were hearing outside the building.

"We all have cellphones, so people were constantly giving people updates — about what was going on, who the victims were, how they were doing," Moser said.

The school had no metal detectors, but current and past students said it had frequent security drills in case of a shooting.

Anxious parents of high school students were told to go to an elementary school to pick up their children.

Joe Bergant, superintendent of schools in Chardon, a town of about 5,100 people, said school was canceled Tuesday and grief counselors would be available to students and families.

"If you haven't hugged or kissed your kid in the last couple of days, take that time," he said.

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